1. Field of the Invention
The present invention relates to a semiconductor phase shifter used in a phased array radar or the like.
2. Description of the Related Art
In a first prior art semiconductor phase shifter (See: Robert V. Garver, "Broad-Band Diode Phase Shifters", IEEE Trans. of Microwave Theory and Techniques, Vol. MTT-20, No. 5, pp. 314-323, May 1972), a T-type high-pass filter and a T-type low-pass filter are switched by arranging switches. This will be explained later in detail.
In the first prior art semiconductor phase shifter, however, since two control biases are required, so that the two switches and are required, a large insertion loss is created.
In a second prior art semiconductor phase shifter (see: JP-A-1-202007), only one control bias is provided. This also will be explained later in detail.
In the second prior art semiconductor phase shifter, however, even if the frequency of propagation signals is shifted a little from the desired frequency, the phase shift deviates, so that the semiconductor phase shifter is narrowband.